Tuesday, May 31, 2011

Winter mite damage is obvious if you use a hand lens

Last week I visited a lawn that was damaged by what was identified and treated as a fungus problem. While various funguses are common in many lawns this year, especially as a result of the wet cold spring, fungi were not responsible for the dead portion of this lawn. The problem was winter feeding activity of mites.

You could see where the mites had started feeding next to the sidewalk and continued to feed almost in a block-like pattern further into the lawn. The area near the sidewalk was fully exposed to the winter sun and was slightly higher than the sidewalk creating an area that dried out during late fall and winter. This is exactly what these winter-feeding mites like, dry hot turf.

Note the stippling on the leaf blade
caused by the feeding activity of the mites.

Note the purpling due to lack of adequate
nutrient movement to the tip of the blade.

Where dead grass and live grass came together, the tips of some of the grass blades were purple. This coloration is common during cold weather due to the lack of nutrient movement from the roots to the leaf tip. In this instance however, the lack of nutrient movement was due to the cellular damage caused by the mites feeding just below and in the purple region. The area of turf in the first photo is dead and will need to be removed and new sod applied. It will not come back on its own as lawns often do when infected by a disease.

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